Gene profiling of the red light signalling pathways in roots

Abstract

Red light, acting through the phytochromes, controls numerous aspects of plant development. Many of the signal transduction elements downstream of the phytochromes have been identified in the aerial portions of the plant; however, very few elements in red-light signalling have been identified specifically for roots. Gene profiling studies using microarrays and quantitative Real-Time PCR were performed to characterize gene expression changes in roots of Arabidopsis seedlings exposed to 1 h of red light. Several factors acting downstream of phytochromes in red-light signalling in roots were identified. Some of the genes found to be differentially expressed in this study have already been characterized in the red-light-signalling pathway for whole plants. For example, PHYTOCHROME KINASE 1 (PKS1), LONG HYPOCOTYL 5 (HY5), EARLY FLOWERING 4 (ELF4), and GIGANTEA (GI) were all significantly up-regulated in roots of seedlings exposed to 1 h of red light. The up-regulation of SUPPRESSOR OF PHYTOCHROME A RESPONSES 1 (SPA1) and CONSTITUTIVE PHOTOMORPHOGENIC 1-like (COP1-like) genes suggests that the PHYA-mediated pathway was attenuated by red light. In addition, genes involved in lateral root and root hair formation, root plastid development, phenylpropanoid metabolism, and hormone signalling were also regulated by exposure to red light. Interestingly, members of the RPT2/NPH3 (ROOT PHOTOTROPIC 2/NON PHOTOTROPIC HYPOCOTYL 3) family, which have been shown to mediate blue-light-induced phototropism, were also differentially regulated in roots in red light. Therefore, these results suggest that red and blue light pathways interact in roots of seedlings and that many elements involved in red-light-signalling found in the aerial portions of the plant are differentially expressed in roots within 1 h of red light exposure.

Oxidative Pentose Phosphate Pathway-Dependent Sugar Sensing as a Mechanism for Regulation of Root Ion Transporters by Photosynthesis

“…The authors showed that the small amount of light that passes through the soil is sufficient to repress AS1 expression in roots. Furthermore, recent microarray experiments identified several genes differentially expressed in roots of dark-grown Arabidopsis seedlings exposed for 1 h to red light (Molas et al, 2006). In agreement with the hypothesis of a direct action of light in roots, three classes of light receptors have been found in Arabidopsis roots: the phytochromes, the cryptochromes, and phototropin (Neff et al, 2000;Quail, 2002).…”

Root-Localized Phytochrome Chromophore Synthesis Is Required for Photoregulation of Root Elongation and Impacts Root Sensitivity to Jasmonic Acid in Arabidopsis

“…For example, R light absorbed by rootlocalized phyA and phyB impacts root phototropism (Kiss et al, 2003) and inhibits root elongation rates (Correll and Kiss, 2005) in Arabidopsis. Recent microarray analyses for roots exposed to R light indicate that the expression of many genes, including a number of genes involved in photomorphogenesis and root development, are regulated by light in roots (Molas et al, 2006). FR light also impacts root growth, i.e.…”

Insight into plant annexin function

“…27 In addition, in maize roots, the xylem water flux sustained by root pressure occurs during the day and is less important at night. 28 More generally, gene profiling of the red light signaling pathways in Arabidopsis roots performed by Molas et al 29 allowed the identification of several factors acting downstream of phytochromes in red-light signaling among which genes involved in lateral root and root hair formation, root plastid development, hormone signaling and phenylpropanoid metabolism.…”